Manufacture of esters of the borneols



' Patented Dec. 29, 1931 No Drawing. Original application .lytic acids.

UNITED STATES PATENT OFFICE KARL STEPI-IAN AND FRITZ ULFLEERS, OF BERLIN-OHARLOTTENBURG, GERMANY, AS-

SIGNORS TO SCKERI'NG-KAHLBAULI AKTIENG-ESELLSCHAFT,

OF BERLIN, GERMANY MANUFACTURE OF ESTERS OF THE BOR'NEOLS 1925. Divided and this application Our invention refers to the manufacture of esters of the borneols (isoborneol and borneol) from camphene in the presence of cata- This application is a division of our co-pending application Serial No. 98,625 filed March 30, 1.926, which matured into Patent No. 1,755,750, dated April 22, 1930.

It is known that camphene can be transformed into isoborneol esters admixed with borneol esters by means of fatty acids, for example aceticacid, when using as catalysts strong mineral acids (for example sulphuric acid, nitric acid or hydrochloric acid) and that the corresponding alcohols can be obtained therefrom by saponification. The esters obtained are, however, not pure because strong mineral acids in secondary reaction attack both the camphene and the esters. This aflects both the purity and the yield of isoborneol.

Esters of substantially greater purity and from them isoborneol of substantially higher melting point can be obtained when mineral acids are caused to react at considerably lower temperatures than is usual.

The attachment of the fatty acids takes place both more quickly and more completely when they are added in quantities which are in excess of that theoretically necessary. The same object may also be obtained by the use of highly concentrated fatty acids.

The reaction takes place extraordinarily quickly. I

The fatty acids employed can be recovered easily and quantitatively from the wash waters by evaporation and heating This invention is illustrated in the following example, the parts being by weight 136 parts of camphene are stirred for some time with 5 1 parts of 91% formic acid and the mixture cooled to below 0 C. 13 parts of 95% sulphuric acid are slowly added to the cold mixture while stirring briskly, care being taken to prevent a rise of temperature until the ester content no longer increases; the sulphuric acid is then allowed to settle and is separated from the ester mixture. An ester mixture of about 95% ester content is obtained. V

filed March 30, 1926, Serial No. 98,625, and in Germany April 11,

filed December 9, 1929. Serial No. 412,928. I

If the 91% formic acid is replaced by 99% formic acid 2 parts of sulphuric'acid will suffice toobtain the highest content in formate, and danger of sidereactions being caused by this acid is still further diminished.

We wish it to be understood that the production of said esters is not limited to the exact proportions and operations described, for obvious modifications will occur to a person skilled in the art. 7

We claim as our. invention:

1. A process of manufacturing esters of the borneols which consists in causing a saturated fatty acid to react upon camphene in the presence of sulphuric acid at a temperature of about 0 C.

2. A process of manufacturing esters of the borneols which consists in causing a saturated fatty acid to reactupon camphene in the presence of a strong mineral acid at a the borneols which consists in causing a highly concentrated saturated fatty acid to react upon camphene in the presence of sulphigic acid at a temperature of about 4:. A process of manufacturing esters of the borneols which consists in causing a highly concentrated saturated fatty acid to react upon camphene in the presence of a strong mineral acid at a temperature of about 0 C.

5. A process of manufacturing esters of the borneols which consists in causing an excess of a saturatedfatty acid to react upon camphene in the presence of sulphuric acid at a temperature of about 0 C.

6. A process of manufacturing esters of the borneols which consistsin causing an excess of a saturated fatty acid to react upon camphene in the presence of a strong mineral acid at a temperature of about 0 C.

' KARL STEPHAN. FRITZ ULFFERS. 

